The genome of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronavirus has a capping modification at the 5′-untranslated region (UTR) to prevent its degradation by host nucleases. These modifications are performed by the Nsp10/14 and Nsp10/16 heterodimers using S-adenosylmethionine as the methyl donor. Nsp10/16 heterodimer is responsible for the methylation at the ribose 2′-O position of the first nucleotide. To investigate the conformational changes of the complex during 2′-O methyltransferase activity, we used a fixed-target serial synchrotron crystallography method at room temperature. We determined crystal structures of Nsp10/16 with substrates and products that revealed the states before and after methylation, occurring within the crystals during the experiments. Here we report the crystal structure of Nsp10/16 in complex with Cap-1 analog (^m7GpppA_m2′-O). Inhibition of Nsp16 activity may reduce viral proliferation, making this protein an attractive drug target.

严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 冠状病毒的基因组在 5'-非翻译区 (UTR) 处进行了加帽修饰，以防止其被宿主核酸酶降解。这些修饰由 Nsp10/14 和 Nsp10/16 异二聚体使用 S-腺苷甲硫氨酸作为甲基供体进行。Nsp10/16 异源二聚体负责第一个核苷酸的核糖 2'-O 位置的甲基化。为了研究复合物在 2'-O 甲基转移酶活性期间的构象变化，我们在室温下使用了固定目标串行同步加速器晶体学方法。我们用底物和产物确定了 Nsp10/16 的晶体结构，这些底物和产物揭示了甲基化前后的状态，在实验过程中发生在晶体内。^m7 GpppA _m2'-O )。抑制 Nsp16 活性可能会减少病毒增殖，使这种蛋白质成为有吸引力的药物靶点。